Pump device

ABSTRACT

A pump device may include a stator provided with a stator core having a ring-shaped part on a center side and a drive coil wound around the stator core, and a partition wall disposed configured to separate a pump chamber from the stator. The partition wall is provided with a protruded part in a bottomed tube-like shape which is protruded on an inner side of the ring-shaped part and an outer peripheral face of a tube shaped part structuring the protruded part is formed with a plurality of protruding parts protruding to an outer side in a radial direction. The stator core is fixed to the protruded part in a state that the plurality of the protruding parts is press-fitted to the ring-shaped part.

CROSS REFERENCE TO RELATED APPLICATION

The present invention claims priority under 35 U.S.C. §119 to JapaneseApplication No. 2011-162569 filed Jul. 25, 2011, the entire content ofwhich is incorporated herein by reference.

FIELD OF THE INVENTION

At least an embodiment of the present invention may relate to a pumpdevice which is provided with a partition wall partitioning a pumpchamber.

BACKGROUND

A vortex pump for pressure-feeding liquid is, for example, disclosed inJapanese Patent Laid-Open No. 2010-119164. The pump device disclosed inthe literature is provided with a stator having a stator core aroundwhich a drive coil is wound, a rotor having an impeller and a drivemagnet in a tube-like shape which surrounds the stator from an outerperipheral side, and a partition wall which is disposed between thestator and the rotor for separating the pump chamber within which theimpeller is disposed from the stator. In the pump device disclosed inthe literature, the stator is fixed to a base plate through an insulatorwhich is utilized when the drive coil is wound around the stator coreand then the stator is fixed to a housing. The housing is a resin moldedbody in which the stator and the base plate are resin-molded by insertmolding and a part of the resin molded body functions as the partitionwall.

In the pump device disclosed in the above-mentioned Patent Literature,two members (insulator and base plate) are disposed between the housingand the stator and thus dimensional tolerance and assembling toleranceare accumulated and, as a result, the positional accuracy of the statorwith respect to the partition wall may be lowered. When the positionalaccuracy of the stator with respect to the partition wall is lowered, itis difficult to control a gap between the stator having the drive coiland the drive magnet of the rotor facing each other through thepartition wall and thus it is difficult to maintain the performance of amanufactured pump device to be substantially the same.

SUMMARY

In view of the problem described above, at least an embodiment of thepresent invention may advantageously provide a pump device in which thestator is capable of being positioned and fixed with a high degree ofaccuracy with respect to the partition wall separating the stator fromthe rotor.

According to at least an embodiment of the present invention, there maybe provided a pump device including a stator provided with a stator corehaving a ring-shaped part on a center side and a drive coil which iswound around the stator core, a rotor provided with an impeller and adrive magnet which faces the stator through a predetermined distance onan outer peripheral side of the stator, and a partition wall which isdisposed between the stator and the rotor for separating a pump chamberin which the impeller is disposed from the stator. The partition wall isprovided with a protruded part in a bottomed tube-like shape which isprotruded on an inner side of the ring-shaped part, an outer peripheralface of a tube shaped part structuring the protruded part is formed witha plurality of protruding parts which protrude from parts in acircumferential direction to an outer side in a radial direction, andthe stator core is fixed to the protruded part in a state that aplurality of protruding parts is press-fitted to the ring-shaped part.

According to at least an embodiment of the present invention, the statoris directly fixed to the partition wall separating the stator from therotor. Therefore, positional accuracy of the stator with respect to thepartition wall can be enhanced. Further, different from a case that thestator core is fixed to the partition wall in a state that the entireperiphery in the circumferential direction of the protruded part ispress-fitted to the ring-shaped part, the stator core is fixed to thepartition wall in a state that a plurality of the protruding partsprovided on the outer peripheral face of the tube shaped part of theprotruded part is press-fitted to the ring-shaped part and thus apress-fitting margin between the partition wall and the stator core issmall. As a result, the stator core is easily press-fitted when thestator core is to be fixed to the partition wall and thus positionalaccuracy of the stator with respect to the partition wall can beenhanced even when the stator is press-fitted and fixed to the partitionwall. Therefore, a gap space between the stator core of the stator andthe drive magnet of the rotor which face each other through thepartition wall can be controlled with a high degree of accuracy.

In accordance with at least an embodiment of the present invention, aninner peripheral face of the ring-shaped part of the stator core isprovided with a plurality of recessed parts to which each of a pluralityof the protruding parts is capable of being press-fitted, and theprotruding parts are press-fitted to the recessed parts. According tothis structure, the stator (stator core) is positioned around the axialline “L” by press-fitting the protruding part to the recessed part.Further, when the rotor provided with the impeller is rotated by themagnetic drive mechanism structured of the drive coil, the stator coreand the drive magnet, the stator is prevented from being turned aroundthe axial line “L” by the reaction force. In addition, since a pluralityof the protruding parts provided on the outer peripheral face of theprotruded part is press-fitted to the recessed parts provided in thering-shaped part, stress at the time of press-fitting is easily releasedfrom each of the protruding parts to the circumferential direction ofthe protruded part. Therefore, deformation and damage of the partitionwall can be prevented when the stator is press-fitted and fixed.

In this case, it is preferable that both side portions in thecircumferential direction of the protruding part are press-fitted to therecessed part, and a clearance is provided between a tip end on an outerside in the radial direction of the protruding part and the recessedpart. According to this structure, stress is restrained from occurringin the radial direction of the protruded part at the time ofpress-fitting and fixing. Therefore, deformation and damage of thepartition wall can be prevented.

In accordance with at least an embodiment of the present invention, theplurality of the protruding parts is formed in the same shape and isdisposed at three or more positions at an equal angular interval.According to this structure, when a plurality of protruding parts ispress-fitted to the ring-shaped part, concentricity of the protrudedpart of the partition wall with the stator core is improved and thus thepositional accuracy of the stator with respect to the partition wall isimproved.

In accordance with at least an embodiment of the present invention, theprotruding part is extended in an axial line direction along the outerperipheral face of the tube shaped part and is provided with a taperedface whose protruding amount to an outer side in the radial directionand to the circumferential direction is increased from a side of abottom part of the protruded part in the bottomed tube-like shape towarda side of an opening end of the protruded part, and a part of theprotruding part on the side of the opening end is press-fitted to thering-shaped part of the stator core. According to this structure, theprotruding part is easily press-fitted to the ring-shaped part of thestator core. Further, only a part of the protruding part is press-fittedto the ring-shaped part of the stator core and thus a press-fittingmargin can be reduced.

In accordance with at least an embodiment of the present invention, thepartition wall is provided with a cylindrical tube part provided on anouter peripheral side of the protruded part and a circular ring-shapedpart which connects an opening end of the protruded part with thecylindrical tube part, the stator is accommodated in a circularring-shaped recessed part for accommodating the stator which is formedof the protruded part, the cylindrical tube part and the circularring-shaped part, and the stator is covered by a sealing agent which ispoured into the circular ring-shaped recessed part for accommodating thestator. According to this structure, even when a press-fitting marginbetween the partition wall and the stator core is small, the stator canbe surely fixed to the partition wall by the sealing agent.

In this case, it is preferable that the protruded part in the bottomedtube-like shape is provided with a protruding portion which protrudes inan axial line direction from an opening of the circular ring-shapedrecessed part for accommodating the stator on a bottom part side of theprotruded part, and an end of the protruding part on the bottom partside of the protruded part is reached to the protruding portion.According to this structure, the ends of the protruding parts which arereached to the protruding portion are respectively fitted to therecessed parts of the ring-shaped part of the stator core and, afterthat, the stator is guided by the protruding parts and is accommodatedin the stator accommodating room.

Further, in this case, it is preferable that the partition wall is aresin molded product, and an inner peripheral face of the tube shapedpart structuring the protruded part is formed with a groove at aposition corresponding to the protruding part formed on the outerperipheral face of the tube shaped part. According to this structure, athickness of the tube shaped part of the protruded part can be setalmost uniform over the entire periphery and thus shrinkage occurred inthe protruded part when the partition wall is molded can be set uniform.Therefore, the cylindricality of the protruded part is improved.

In accordance with at least an embodiment of the present invention, anouter peripheral face of the tube shaped part structuring the protrudedpart is provided with a positioning part which is abutted with thering-shaped part of the stator core from a side of an opening end of theprotruded part in the bottomed tube-like shape for positioning thestator in an axial line direction, and the positioning part and theprotruding part are formed at a separated position from each other in acircumferential direction. According to this structure, positioning ofthe stator in the axial line direction is easily performed.

In accordance with at least an embodiment of the present invention, asupport shaft which rotatably supports the rotor is fixed to an innerside face of the bottom part of the protruded part. According to thisstructure, both of the support shaft supporting the rotor and the statorare fixed to the protruded part and thus a relative positional accuracyof the rotor supported by the support shaft to the stator is improved.

Further, in accordance with at least an embodiment of the presentinvention, a support shaft which rotatably supports the rotor is fixedto an inner side face of the bottom part of the protruded part, therotor is provided with a bearing part in a tube-like shape, the bearingpart is disposed on an inner side of the protruded part in a state thatthe support shaft is inserted into a center hole of the bearing part, awasher for adjusting a position in the axial line direction of the rotoris fitted between the bottom part of the protruded part and the bearingpart, the washer is formed with a turning prevention part protruding toan outer side in the radial direction from an outer circumferential edgeportion of the washer, and the turning prevention part is fitted to thegroove formed on the inner peripheral face of the tube shaped part.According to this structure, a relative positional adjustment of therotor to the stator in the axial line direction can be performed byfitting of the washer. Further, since the turning prevention part andthe groove are engaged with each other, the washer is prevented frombeing turned around the axial line when the rotor is rotated.

Further, the pump device in accordance with at least an embodiment ofthe present invention may include a first case which structures thepartition wall and is provided with a circular ring-shaped protrudedpart on an inner side of an outer peripheral wall, a second case whichis provided with a circular ring-shaped stepped part into which thecircular ring-shaped protruded part is coaxially inserted and whichpartitions the pump chamber on an inner peripheral side of the circularring-shaped stepped part together with the first case, and an O-ringwhich is attached on a circular outer peripheral face of the circularring-shaped protruded part and is crushed between the circular outerperipheral face of the circular ring-shaped protruded part and acircular inner peripheral face of the circular ring-shaped stepped partin a direction perpendicular to an axial line of the circularring-shaped protruded part.

Further, in accordance with at least an embodiment of the presentinvention, the second case includes a bottom plate part, a side wallpart in a ring shape which is stood up from an outer peripheral sideportion of the bottom plate part, and a circular recessed part which isformed of the bottom plate part and the side wall part. An innerperipheral face on an upper side of the side wall part is formed withthe circular ring-shaped stepped part, and a liquid flow passage isstructured between the circular ring-shaped protruded part of the firstcase and the circular recessed part of the second case at a position onan inner side with respect to the circular ring-shaped stepped part.

Other features and advantages of the invention will be apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings that illustrate, by way of example, variousfeatures of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the accompanying drawings which are meant to be exemplary,not limiting, and wherein like elements are numbered alike in severalFigures, in which:

FIGS. 1( a), 1(b) and 1(c) are perspective views and a front viewshowing a pump device in accordance with an embodiment of the presentinvention.

FIGS. 2( a) and 2(b) are cross-sectional views showing a pump device inaccordance with an embodiment of the present invention.

FIG. 3 is an exploded perspective view showing a pump device inaccordance with an embodiment of the present invention.

FIG. 4( a) is a perspective view showing a rotor and FIG. 4( b) is aperspective view showing a stator.

FIGS. 5( a) and 5(b) are perspective views showing a lower case.

FIGS. 6( a) and 6(b) are perspective views showing an upper case.

FIGS. 7( a) and 7(b) are partly enlarged perspective views showing astator accommodating room of an upper case and the like.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A pump device in accordance with an embodiment of the present inventionwill be described below with reference to the accompanying drawings. Inthe following description, for convenience of explanation, upper andlower sides of a pump device are described according to an upper andlower direction in the drawing. Further, a side from which a suctionpipe and a discharge pipe are protruded is referred to as a front sideof the pump device and its opposite side is referred to as a rear sideand an arrangement direction of the suction pipe and the discharge pipeis referred to as a widthwise direction of the device.

(Entire Structure)

FIG. 1( a) is a perspective view showing a pump device in accordancewith an embodiment of the present invention which is viewed from aforward oblique upper side, FIG. 1( b) is a perspective view showing thepump device which is viewed from a rearward oblique upper side, and FIG.1 (c) is a front view showing the pump device. A pump device 1 inaccordance with an embodiment of the present invention is a vortex pumpwhich pressure-feeds liquid such as refrigerant. The pump device 1 isprovided with a pump case 2 which is formed in a flat rectangular prismshape as a whole. The pump case 2 is made of resin such as PPS(polyphenylene sulfide). A suction pipe 3 and a discharge pipe 4 areprotruded in parallel toward the front side from a front face 2 a of thepump case 2. A wiring outlet part 6 for taking out lead wires 5 from aninner side of the pump case 2 is provided at a corner portion 2 blocated on a front left side between the front face 2 a of the pump case2 and a side face adjacent to the front face 2 a in a clockwisedirection. The lead wires 5 are extended out from a midway position inan axial line “L” direction (height direction) of the pump device 1through the wiring outlet part 6 toward an obliquely front side. Thelead wires 5 are extended longer than the suction pipe 3 and thedischarge pipe 4 and a connector 7 is attached to tip ends of the leadwires 5.

An inclined face 2 c (see FIG. 1( c)) intersecting the front face 2 aand the side face and extending in the axial line “L” direction isformed at the corner portion 2 b located on the front left side of thepump case 2 where the wiring outlet part 6 is provided by obliquelycutting out a tip end of the corner portion 2 b. Further, a hook 8 isprovided at the corner portion 2 b located on the front left side forlocking the lead wires 5 when the lead wires 5 are extended out alongthe inclined face 2 c. The hook 8 is extended in a directionperpendicular to the axial line “L” at a center position in the axialline “L” direction of the inclined face 2 c so as to have apredetermined space between the inclined face 2 c and the hook 8.Further, the hook 8 is extended with a constant width from the frontface 2 a side toward the side face.

The pump case 2 is structured of a lower case (second case) 11 and anupper case (first case or partition wall) 12 which are superposed oneach other in the upper and lower direction. The suction pipe 3 and thedischarge pipe 4 are protruded from the front face of the lower case 11.The wiring outlet part 6 is structured at the corner portion on thefront left side of the upper case 12. The hook 8 is provided on thelower case 11. In this embodiment, a corner portion 2 f on the rearright side of the pump case 2 which is located at a position diagonal tothe wiring outlet part 6 is provided with a turning prevention mechanism13 for preventing relative turning of the lower case 11 to the uppercase 12 when the lower case 11 and the upper case 12 are superposed oneach other.

FIG. 2( a) is a longitudinal sectional view showing the pump device 1which is cut by the “X-X” line in FIG. 1( a) and FIG. 2( b) is alongitudinal sectional view showing the pump device 1 which is cut bythe “Y-Y” line in FIG. 1( a). FIG. 3 is an exploded perspective viewshowing the pump device 1. FIG. 4( a) is a perspective view showing arotor and FIG. 4( b) is a perspective view showing a stator.

As shown in FIGS. 2( a) and 2(b) and FIG. 3, the lower case 11 and theupper case 12 are superposed on each other in a partially overlappedstate in a direction perpendicular to axial line “L”. A partitionedchamber 20 for accommodating a rotor and for forming a pump chamber isstructured between the lower case 11 and the upper case 12. A rotor 23provided with a circular ring-shaped impeller 21 and a drive magnet 22and a support shaft 24 which rotatably supports the rotor 23 aredisposed in the partitioned chamber 20. Further, an outer peripheralside portion of the partitioned chamber 20 is structured to be acircular ring-shaped pump chamber 25 through which liquid ispressure-fed by the impeller 21 and the impeller 21 structuring therotor 23 is disposed within the pump chamber 25. An O-ring 26 isdisposed between the lower case 11 and the upper case 12 for preventingleakage of liquid from the partitioned chamber 20. A stator 29 providedwith a drive coil 27 and a stator core 28 on which the drive coil 27 ismounted and a base plate 30 are disposed on an upper side of the uppercase 12 which is opposite to the side where liquid is pressure-fed, inother words, on an opposite side to the partitioned chamber 20 withrespect to the upper case 12 (opposite side to the lower case 11). Thedrive magnet 22, the stator core 28, and the drive coil 27 wound aroundthe stator core 28 structure a magnetic drive mechanism for rotationallydriving the impeller 21.

A liquid flow passage 31 is formed on a bottom face and a ceiling faceof the pump chamber 25 over a predetermined angular range around theaxial line “L”. More specifically, a lower side liquid flow passage 31 aformed of a circular arc groove having a semicircular cross-sectionalshape is formed on the bottom face of the pump chamber 25 which isstructured of the lower case 11, and an upper side liquid flow passage31 b formed of a circular arc groove having a semicircularcross-sectional shape is formed on the ceiling face of the pump chamber25 which is structured of the upper case 12. The lower side liquid flowpassage 31 a and the upper side liquid flow passage 31 b are superposedon each other when viewed in the axial line “L” direction. In thisembodiment, the liquid flow passage 31 is formed over an angular rangeapproximately larger than 270° around the axial line “L”.

In the pump chamber 25, a suction port 3 a (see FIG. 5( a)) which is incommunication with the suction pipe 3 is provided at a portion of thelower case 11 where one end of the liquid flow passage 31 is located anda discharge port 4 a (see FIG. 5( a)) which is in communication with thedischarge pipe 4 is provided at a portion of the lower case 11 where theother end of the liquid flow passage 31 is located. A portion of thebottom face of the pump chamber 25 which is located between the suctionport 3 a and the discharge port 4 a is formed as a lower side blockingpart 32 a where the lower side liquid flow passage 31 a is not formed.Similarly, a portion of the ceiling face of the pump chamber 25 which islocated between the suction port 3 a and the discharge port 4 a isformed as an upper side blocking part 32 b where the upper side liquidflow passage 31 b is not provided.

A support shaft 24 is made of stainless steel and its lower end portionis fixed to a support shaft fixing recessed part 60 which is provided inthe lower case 11. Further, its upper end portion is fixed to a supportshaft fixing recessed part 82 which is provided at a center of a bottompart 81 of a center protruded part 80 formed in a bottomed tube-likeshape that is provided at the center portion of the upper case 12. Thesupport shaft fixing recessed part 82 is provided at a center of aninner side face of the bottom part 81.

The rotor 23 is provided with, as shown in FIG. 4( a), a disk part 40, abearing part 41 in a cylindrical tube shape which is protruded upwardfrom a center of an upper face of the disk part 40, and a magnet holdingcylindrical tube part 42 which is protruded upward from the upper faceof the disk part 40 so as to coaxially surround the bearing part 41 witha predetermined distance from the bearing part 41, which are made ofresin such as PPS. The predetermined distance between the bearing part41 and the cylindrical tube part 42 is a distance in which the stator 29is capable of being accommodated therebetween through the upper case 12.The rotor 23 is rotatable around the axial line “L” of the support shaft24 in a state that the support shaft 24 is inserted into a center hole41 a of the bearing part 41 and the bearing part 41 is disposed on aninner side of the center protruded part 80 of the upper case 12. Onepiece or plural pieces of the washer 43 is fitted between an upper endof the bearing part 41 and the bottom part 81 of the center protrudedpart 80 and the position of the rotor 23 in the axial line “L” directionwith respect to the stator 29 is adjusted by fitting of the washer 43(see FIGS. 2( a) and 2(b)). In this embodiment, two pieces of the washerare used. For example, when one or two pieces of a washer 43 whosethickness is 0.2 mm and a washer 43 whose thickness is 0.3 mm areselected, a total thickness of the washers 43 can be adjusted in a rangefrom 0.2 mm to 0.6 mm with an interval of 0.1 mm.

A yoke 44 in a cylindrical tube shape is held by an inner peripheralface of the magnet holding cylindrical tube part 42 and the drive magnet22 in a cylindrical tube shape is held by an inner peripheral face ofthe yoke 44. The yoke 44 is integrally formed with the rotor 23 byinsert molding and the drive magnet 22 is adhesively fixed to the yoke44. An outer peripheral portion on an outer peripheral side in the diskpart 40 with respect to the cylindrical tube part 42 is structured asthe impeller 21.

An outer peripheral portion of the impeller 21 is formed with recessedparts 45 which are formed in two rows in the upper and lower directionat an equal angular interval in the circumferential direction. Therecessed parts 45 are provided with upper side recessed parts 46, whichare formed by cutting a circumferential edge of an upper face of thedisk part 40 in a circular arc shape, and lower side recessed parts 47which are formed by cutting a circumferential edge of an under face ofthe disk part 40 in a circular arc shape. Portions between the recessedparts 45 adjacent to each other in the circumferential direction areformed as blades 48 which are respectively extended in a radialdirection. A portion between the upper side recessed parts 46 and thelower side recessed parts 47 which are adjacent to each other in theupper and lower direction is extended in the circumferential directionand is formed to be a rib 49 partitioning the respective blades 48 inthe upper and lower direction. The impeller 21 is, as shown in FIGS. 2(a) and 2(b), disposed in the pump chamber 25.

The stator 29 is disposed within a stator accommodating room (statoraccommodating circular ring-shaped recessed part) 83 which is formed ina circular ring-shaped recessed part and is provided on an outerperipheral side of the center protruded part 80 and on an upper faceside of the upper case 12. A stator core 28 is, as shown in FIG. 4( b),provided with a ring-shaped part 50 on its center side and a pluralityof salient poles 51 which is protruded from the ring-shaped part 50 toan outer side in the radial direction. A drive coil 27 is wound aroundeach of a plurality of the salient poles 51. As shown in FIGS. 2( a) and2(b), each of the salient poles 51 is oppositely disposed through theupper case 12 in a direction perpendicular to the axial line “L” to thedrive magnet 22 of the rotor 23 which is disposed within the partitionedchamber 20 that forms a magnet accommodating space in which the circularring-shaped drive magnet 22 is accommodated. The upper case 12 isdisposed between the rotor 23 and the stator 29 to be functioned as apartition wall separating the pump chamber 25 and the magnetaccommodating space from the stator 29.

The stator core 28 is structured so that a plurality of plate-shapedcore pieces 52 having the same shape which are formed by die cutting ofa thin plate-shaped magnetic steel plate is laminated in the upper andlower direction and a laminated direction of the plate-shaped corepieces 52 is the axial line “L” direction. An inner peripheral face ofthe ring-shaped part 50 of the stator core 28 is formed with three innerside recessed parts 53 whose cross-sectional shape in a directionperpendicular to the axial line “L” is a circular arc contour shape atan equal angular interval around the axial line “L”. Three inner siderecessed parts 53 are the same shape and are extended in the axial line“L” direction. The depths in the radial direction of the respectiveinner side recessed parts 53 are the same as each other and itscross-sectional shape is the same as each other at each position in theaxial line “L” direction.

A base plate 30 is disposed in an upper space 87 which is provided on aninner side of a frame-shaped outer peripheral wall 86 protruding from anupper face of the upper case 12 to an upper side along itscircumferential edge. The base plate 30 serves as a circuit board forsupplying an electric current to the drive coil 27 wound around thestator core 28 and covers the stator 29 disposed within the statoraccommodating room 83 from the upper side. A face on the stator core 28side of the base plate 30 is connected with the lead wires 5, which aredrawn out to an outer side of the pump case 2 through the wiring outletpart 6. The wiring outlet part 6 is, as shown in FIG. 3, provided with awiring outlet port 33 which is formed by cutting out an outer peripheralwall 86, a wire placing part 34 for arranging and placing the lead wires5 in one row which are drawn out from the inner side of the pump case 2to the outer side through the wiring outlet port 33, and a fixing member35 which is fixed to the upper case 12 so as to close the wiring outletport 33 from the upper side of the base plate 30 for sandwiching thelead wires 5 arranged on the wire placing part 34 between the wireplacing part 34 and the fixing member 35 and thereby their coatings arefixed in a pressed state.

In this embodiment, as shown in FIGS. 1( a) and 1(b), a potting agent 16(sealing agent) is poured into the stator accommodating room 83 and theupper space 87 of the upper case 12 so as to reach the upper end of theouter peripheral wall 86 and thus the stator 29 and the base plate 30are covered and fixed by the potting agent 16. The potting agent 16 isresin having insulation property such as epoxy, acrylic, or siliconresin.

When an exciting current is supplied to the drive coil 27 from theconnector 7 through the lead wires 5 and the base plate 30, the rotor 23is rotated around the axial line “L”. As a result, liquid is sucked intothe pump chamber 25 through the suction pipe 3, pressurized in the pumpchamber 25 and then discharged from the discharge pipe 4. The motor(rotor 23, stator 29 and base plate 30) which drives the pump device 1in this embodiment is a three-phase brushless motor and three Hallelements not shown for detecting a position of the drive magnet 22 ofthe rotor 23 are disposed on the base plate 30. When the order of anexciting current supplied to the drive coil 27 is reversed, the rotor 23is rotated in the reverse direction and thus, liquid is sucked throughthe discharge pipe 4, pressurized in the pump chamber 25 and thendischarged from the suction pipe 3.

(Lower Case)

FIG. 5( a) is a perspective view showing the lower case 11 which isviewed from an upper side and FIG. 5( b) is a perspective view showingthe lower case 11 which is viewed from a lower side. The lower case 11is provided with a bottom plate part 61, a ring shaped side wall part 62which is stood up from an outer peripheral side portion of the bottomplate part 61 so as to extend to an upper side, and a circular recessedpart 63 which is formed by the bottom plate part 61 and the side wallpart 62. A contour shape of the side wall part 62 which is viewed in theaxial line “L” direction is a substantially rectangular shape and aplanar shape of the lower case 11 viewed in the axial line “L” directionis a substantially rectangular shape. The side wall part 62 is providedwith a flat upper end face 62 a and the upper end face 62 a is an upperend face of the lower case 11. The pump chamber 25 is structured so asto be a ring shape along the circumferential edge of the circularrecessed part 63. A support shaft fixing recessed part 60 is provided atthe center of a circular bottom face of the circular recessed part 63.

A circular ring-shaped recessed part 64 is formed on an outer peripheralside of the support shaft fixing recessed part 60 coaxially with thesupport shaft fixing recessed part 60. A portion between the supportshaft fixing recessed part 60 and the circular ring-shaped recessed part64 is formed to be an inner side ring-shaped protruded face 65 and aportion on an outer peripheral side of the circular ring-shaped recessedpart 64 is formed to be an outer side ring-shaped protruded face 66. Theouter side ring-shaped protruded face 66 structuring the circularrecessed part 63 is formed with a lower side liquid flow passage 31 astructuring a bottom face of the pump chamber 25 and a lower sideblocking part 32 a along its circumferential edge. A circularring-shaped end face portion 67 of the outer side ring-shaped protrudedface 66 which is adjacent to the inner side of pump chamber 25 faces thedisk part 40 of the rotor 23 which is disposed within the partitionedchamber 20 through a minute gap “G1” (see FIGS. 2( a) and 2(b)). In thecircular ring-shaped end face portion 67, two grooves 67 a having aconstant width by which the lower side liquid flow passage 31 a is incommunication with the circular ring-shaped recessed part 64 are formedat positions separated from each other by 180°

A circular ring-shaped stepped part 68 is provided on an upper sideportion of the circular recessed part 63, in other words, on an innerperipheral face of an upper side portion of the side wall part 62. Thecircular ring-shaped stepped part 68 is provided with a circularring-shaped end face 68 a, which is extended in a radial direction froma midway position in the axial line “L” direction of the innerperipheral face of the side wall part 62, and a circular innerperipheral face 68 b which is extended to an upper side from an outercircumferential edge of the circular ring-shaped end face 68 a. Thecircular ring-shaped stepped part 68 forms a circular recessed parthaving a diameter larger than a circular recessed part 63 on an upperend portion of the lower case 11.

The suction pipe 3 and the discharge pipe 4 are protruded in parallelfrom the front face of the side wall part 62. An inclined face 2 c and ahook 8 are provided at the corner portion 2 b of the lower case 11 onthe front left side which is adjacent to the discharge pipe 4 of theside wall part 62. A turning prevention recessed part 69 structuring theturning prevention mechanism 13 is provided at a corner portion 2 f onthe rear right side of the side wall part 62. The turning preventionrecessed part 69 is a recessed part which is recessed to a lower sidefrom the upper end face 62 a. Further, the turning prevention recessedpart 69 is cut out from the outer peripheral side and its innerperipheral face is exposed to the outer side of the lower case 11.

(Upper Case)

FIG. 6( a) is a perspective view showing the upper case 12 which isviewed from an upper side and FIG. 6( b) is a perspective view showingthe upper case 12 which is viewed from a lower side. The upper case 12is, as shown in FIG. 6( a), provided with a center protruded part 80 towhich the ring-shaped part 50 of the stator core 28 is fitted, acylindrical tube part 89, which is coaxially structured with the centerprotruded part 80 and with which the outer peripheral faces of thesalient poles 51 of the stator core 28 are abutted, and an inner sidering-shaped part 90 which connects an opening end of the centerprotruded part 80 with a lower end part of the cylindrical tube part 89.Further, the upper case 12 is, as shown in FIG. 6( b), provided with acircular ring-shaped protruded part 91, which is coaxially structuredwith the center protruded part 80 and the cylindrical tube part 89 on anouter peripheral side of the cylindrical tube part 89 and is protrudedto a lower side, an outer side ring-shaped part 92, which connects anupper end part of the cylindrical tube part 89 with an upper end part ofthe circular ring-shaped protruded part 91, and a projecting part 93which projects from an upper end part of the circular ring-shapedprotruded part 91 to an outer peripheral side.

A contour shape of the projecting part 93 is a roughly rectangular shapeand the corner portion 2 b on the front left side is cut out obliquelyto form the inclined face 2 c. The outer peripheral wall 86 forpartitioning an upper space 87 in which the base plate 30 is disposed isprotruded to the upper side from an outer circumferential edge of theprojecting part 93 except the corner portion 2 b on the front left sidewhich is provided with the cut-out portion. In the corner portion 2 b onthe front left side having the cut-out portion, the outer peripheralwall 86 is located at an inner position from an outer circumferentialedge of the projecting part 93. Further, in the corner portion 2 b onthe front left side, the outer peripheral wall 86 is cut out with aconstant width in a rectangular shape and the cut-out part is formed asthe wiring outlet port 33. A portion between the wiring outlet port 33and the outer circumferential edge of the projecting part 93 is the wireplacing part 34. An upper face of the wire placing part 34 is formedwith wire holding grooves 36 a whose cross section is a circular arcshape and which are extended in parallel to an outer side in the radialdirection so as to correspond to the number of the lead wires 5.Further, an under face of the fixing member 35 is formed with wireholding grooves 36 b corresponding to the wire holding grooves 36 b (seeFIG. 1( c)). The lead wires 5 are sandwiched between the wire holdinggrooves 36 a and the wire holding grooves 36 b in the upper and lowerdirection and are fixed in a state that their coatings are pressed.

The corner portion 2 f on the rear right side of the projecting part 93located at a diagonal position to the wiring outlet part 6 is formedwith a turning preventing protruded part 97 in a circular cylindricalshape which is protruded to the lower case 11 side. The turningpreventing protruded part 97 is capable of being fitted to the turningprevention recessed part 69 provided in the lower case 11 and structuresthe turning prevention mechanism 13 together with the turning preventionrecessed part 69.

The stator accommodating room 83 in which the stator 29 is disposed isstructured of faces of the center protruded part 80, the cylindricaltube part 89 and the inner side ring-shaped part 90 on an opposite sidewith respect to the lower case 11. The center protruded part 80 isprovided with a protruding portion 80 a, which is protruded to an upperside from an opening of the stator accommodating room 83, on a side ofthe bottom part 81. A thickness in the radial direction of thecylindrical tube part 89 is formed thinner than a thickness in theradial direction of the center protruded part 80.

A circular ring-shaped lower end face 94 of the circular ring-shapedprotruded part 91 is formed with an upper side liquid flow passage 31 band an upper side blocking part 32 b, which structures a ceiling face ofthe pump chamber 25, at a midway position in the radial direction on aninner side with respect to the circular ring-shaped stepped part 68. Inthe circular ring-shaped lower end face 94, a circular ring-shaped endface portion 94 a which is adjacent to an inner side of the pump chamber25 faces the disk part 40 of the rotor 23 disposed within thepartitioned chamber 20 through a minute gap “G2” (see FIGS. 2( a) and2(b)2).

A radial direction protruded part 96 protruding to an outer side by apredetermined dimension in the radial direction is provided on an upperend portion of a circular outer peripheral face 95 of the circularring-shaped protruded part 91. The radial direction protruded part 96 isprovided with a circular ring-shaped end face 96 a, which is extended toan outer side in the radial direction from a midway position in theaxial line “L” direction of the circular ring-shaped protruded part 91so as to face the lower case 11, and a circular outer peripheral face 96b which is extended to an upper side from an outer circumferential edgeof the circular ring-shaped end face 96 a so as to face the outer sidein the radial direction.

In this embodiment, when the upper case 12 and the lower case 11 are tobe superposed on each other to partition the pump chamber 25(partitioned chamber 20), an O-ring 26 is mounted on the circular outerperipheral face 95 of the circular ring-shaped protruded part 91 of theupper case 12. In this case, a lubricant is applied to the O-ring 26.Further, the support shaft 24 is previously fixed to the support shaftfixing recessed part 82 of the upper case 12 and the rotor 23 isdisposed in the circular recessed part 63 of the lower case 11 so thatthe support shaft 24 is capable of being inserted into the bearing part41. Next, the circular ring-shaped protruded part 91 of the upper case12 is inserted into the inner side of the circular ring-shaped steppedpart 68 of the lower case 11. After that, the upper case 12 and thelower case 11 are relatively come close to each other so that thecircular ring-shaped lower end face 94 of the circular ring-shapedprotruded part 91 (circular ring-shaped end face portion which islocated on the outer peripheral side with respect to the upper sideliquid flow passage 31 b and the upper side blocking part 32 b) isabutted with the circular ring-shaped end face 68 a of the circularring-shaped stepped part 68 of the lower case 11.

In this case, the circular outer peripheral face 96 b of the radialdirection protruded part 96 of the upper case 12 is abutted with thecircular inner peripheral face 68 b of the circular ring-shaped steppedpart 68 of the lower case 11 and thus the upper case 12 is positioned inthe radial direction by the lower case 11. Further, the O-ring 26 iscrushed in the radial direction between the circular outer peripheralface 95 of the circular ring-shaped protruded part 91 of the upper case12 and the circular inner peripheral face 68 b of the lower case 11 in asandwiched state between the circular ring-shaped end face 96 a of theradial direction protruded part 96 and the circular ring-shaped end face68 a of the circular ring-shaped stepped part 68. As a result, theleakage of liquid from the partitioned chamber 20 is prevented. In thisembodiment, when the circular ring-shaped protruded part 91 of the uppercase 12 is inserted into an inner side of the circular ring-shapedstepped part 68 of the lower case 11, the turning preventing protrudedpart 97 of the turning prevention mechanism 13 is fitted to the turningprevention recessed part 69 provided in the lower case 11 and thus thelower case 11 and the upper case 12 are prevented from being relativelyturned to each other around the axial line “L”. Therefore, the O-ring 26is prevented from being twisted in the circumferential direction in astate that the O-ring 26 is crushed in the radial direction and thus,when the pump chamber 25 is to be partitioned, the damage of the O-ring26 is prevented. When the upper case 12 is superposed on the lower case11 to form the pump chamber 25 (partitioned chamber 20) in a partitionedstate, the lower end of the support shaft 24 penetrated through thebearing part 41 of the rotor 23 is inserted and fixed to the supportshaft fixing recessed part 60 of the lower case 11 and the support shaft24 and the center protruded part 80 are set to be in a coaxial state.Further, the rotor 23 is supported by the support shaft 24 in arotatable state around the support shaft 24.

The tube shaped part 84 structuring the center protruded part 80 isprovided with an outer peripheral face and an inner peripheral facewhich are formed in a tapered shape whose diameter is enlarged from aside of the bottom part 81 toward a side of an opening end 80 b alongthe axial line “L” direction. The outer peripheral face of the tubeshaped part 84 is formed with three stator fixing protruding parts 85which are protruded to outer sides in a radial direction from parts inthe circumferential direction. The three stator fixing protruding parts85 are provided with the same shape and are formed at an equal angularinterval around the axial line “L”. Each of the stator fixing protrudingparts 85 is formed so that its cross section perpendicular to the axialline “L” is a circular arc contour shape and is extended in the axialline “L” direction along the outer peripheral face of the centerprotruded part 80. Further, each of the stator fixing protruding parts85 is provided with a tapered face whose protruding amount to an outerside in the radial direction and in the circumferential direction isincreased from a side of the bottom part 81 toward a side of the openingend, in other words, from the upper side to the lower side. An upper end85 a on the bottom part 81 side of each of the three stator fixingprotruding parts 85 is reached to a protruding portion 80 a whichprotrudes in the center protruded part 80 upward from the opening of thestator accommodating room 83, and a lower end of each of the threestator fixing protruded parts 85 on the inner side ring-shaped part 90side is reached downward with respect to a positioning part 88 describedbelow.

Further, the outer peripheral face of the tube shaped part 84 of thecenter protruded part 80 is formed with a positioning part 88 so as tobe abutted with the ring-shaped part 50 of the stator core 28 from theunderside in the axial line “L” direction to position the stator core 28in the axial line “L” direction. The positioning part 88 is a protrudedpart in a circular arc shape which is extended in a circumferentialdirection along the outer peripheral face of the tube shaped part 84 andis provided at three positions in the circumferential direction. Anupper end face of the positioning part 88 which is abutted with thestator core 28 is a flat face which is perpendicular to the axial line“L”. The positioning part 88 and the stator fixing protruding part 85are formed at a separated position in the circumferential direction anda gap space 88 a is provided between the positioning part 88 and thestator fixing protruded part 85 in the circumferential direction. Threepieces of a plate-shaped rib 98 are provided between the positioningpart 88 and the cylindrical tube part 89 so as to extend in a radialdirection and connect the positioning part 88 with the cylindrical tubepart 89. Strength of the stator accommodating room 83 of the upper case12 is assured by the ribs 98.

An inner peripheral face of the tube shaped part 84 of the centerprotruded part 80 is formed with three grooves 99 extending in the axialline “L” direction at corresponding positions to the respective statorfixing protruding parts 85 formed on the outer peripheral face of thetube shaped part 84. In other words, the inner peripheral face of thetube shaped part 84 of the center protruded part 80 is formed with threegrooves 99 having the same shape at an equal angular interval around theaxial line “L” of the support shaft 24. The cross-sectional shapeperpendicular to the axial line “L” of each of the grooves 99 issemicircular and the groove 99 is extended in the axial line “L”direction along the inner peripheral face of the center protruded part80. Further, a width in the circumferential direction of each of thegrooves 99 is gradually increased from a side of the bottom part 81toward a side of the opening end 80 b.

(Fixing Structure of Stator)

FIGS. 7( a) and 7(b) are partly enlarged views showing a statoraccommodating room of an upper case and the like. FIG. 7( a) is a viewshowing a state that the stator 29 is not accommodated in the statoraccommodating room and FIG. 7( b) is a view showing a state that thestator 29 is accommodated in the stator accommodating room. After thedrive coil 27 is wound around each of the salient poles 51, the statorcore 28 is fixed to the inside of the stator accommodating room 83 ofthe upper case 12. More specifically, in a state that the stator fixingprotruding part 85 is fitted to the inner side recessed part 53 of thering-shaped part 50 of the stator core 28, the stator 29 is insertedinto the stator accommodating room 83 and, after that, the lower endportion 85 b of the stator fixing protruding part 85 (part on theopening end 80 b side of the center protruded part 80) is press-fittedto the inner side recessed part 53 of the ring-shaped part and therebythe stator 29 is fixed to the upper case 12. In this embodiment, adiameter on an inner side of the ring-shaped part 50 of the stator core28 is larger than that of the tube shaped part 84 of the centerprotruded part 80 and thus, a gap space is structured between the innerside of the ring-shaped part 50 and the tube shaped part 84 except theportions of the stator fixing protruding parts 85. Further, a curvatureof the inner side recessed part 53 of the ring-shaped part 50 of thestator core 28 is larger than that of the lower end portion 85 b of thestator fixing protruding part 85 and thus only a tip end part of thelower end portion 85 b of the stator fixing protruding part 85 ispress-fitted to the bottom part of the inner side recessed part 53 ofthe ring-shaped part 50. In other words, a gap space is formed betweenthe side faces in the circumferential direction of the lower end portion85 b and the inner side recessed part 53.

In this embodiment, the upper end 85 a on the bottom part 81 side of thestator fixing protruding part 85 is reached to the protruding portion 80a of the center protruded part 80 which is protruded upward from theopening of the stator accommodating room 83. Therefore, when the stator29 is to be fitted to the stator accommodating room 83, the upper end 85a of each of the stator fixing protruding parts 85 is easily fitted tothe inner side recessed part 53 of the ring-shaped part 50 of the statorcore 28. Further, the stator fixing protruding part 85 is formed in atapered face which is widened toward the lower side and thus, when thestator 29 is inserted into the stator accommodating room 83, at first,the stator 29 is guided to a lower side by the stator fixing protrudingparts 85. Then, the positioning part 88 is abutted with the ring-shapedpart 50 of the stator core 28 from the underside to position the stator29 in the axial line “L” direction. Further, the upper end faces of thepositioning parts 88 are abutted with the stator core 28 and thus theattitude of the stator core 28 is determined. In this embodiment, thestator 29 is positioned and fixed in a state that the lower end portions85 b of the stator fixing protruding parts 85 are press-fitted to theinner side recessed parts 53 of the ring-shaped part 50 of, for example,one piece of the plate-shaped core piece 52 structuring the stator core28.

When the stator 29 is fixed to the inside of the stator accommodatingroom 83 of the upper case 12, the salient poles 51 of the stator core 28around which the drive coil 27 is wound and the drive magnet 22 of therotor 23 which is disposed in the partitioned chamber 20 are faced eachother through the tube shaped part 84 of the upper case 12. In thisstate, a potting agent 16 is poured into the stator accommodating room83. The potting agent 16 is flowed into a space structured between theinner side face of the ring-shaped part 50 and the tube shaped part 84and thereby the stator 29 is covered by the potting agent 16.

In this embodiment, as shown in FIGS. 2( a) and 2(b), one or pluralwashers 43 are fitted between the upper end face of the bearing part 41of the rotor 23 and the bottom part 81 of the protruded part and therebythe magnetic center position in the axial line “L” direction of thedrive magnet 22 mounted on the rotor 23 is shifted to a lower side withrespect to the magnetic center position in the axial line “L” directionof the stator core 28. As a result, the rotor 23 is urged upward by amagnetic attraction force acted between the stator core 28 and the drivemagnet 22. In this embodiment, turning prevention parts 43 a in asemicircular shape are formed in each of the washers 43 so as toprotrude to an outer side in the radial direction from its outercircumferential edge portion. Further, each of the turning preventionparts 43 a is fitted to each of the grooves 99 formed on the innerperipheral face of the center protruded part 80 and thereby the washer43 is prevented from being turned around the axial line “L” when therotor 23 is rotated. Further, as described above, one or two pieces ofthe washers 43 whose thickness is 0.2 mm and 0.3 mm are selectivelyused. In this case, when two turning prevention parts 43 a are providedin the washer 43 whose thickness is 0.2 mm and three turning preventionparts 43 a are provided in the washer 43 whose thickness is 0.3 mm, thewasher 43 whose thickness is 0.2 mm and the washer 43 whose thickness is0.3 mm are easily distinguished from each other.

(Operation and Effect)

According to this embodiment, the stator 29 is directly fixed to theupper case 12 (partition wall or first case) which partitions the stator29 from the rotor 23. Therefore, positional accuracy of the stator 29with respect to the upper case 12 (partition wall) can be enhanced.Further, different from a case that the stator core 28 is fixed to theupper case 12 in a state that the entire periphery in thecircumferential direction of the center protruded part 80 ispress-fitted to the ring-shaped part 50 of the stator 29, in thisembodiment, the stator core 28 is fixed to the upper case 12 in a statethat three stator fixing protruding parts 85 provided on the outerperipheral face of the tube shaped part 84 of the center protruded part80 are press-fitted to the ring-shaped part 50 and thus a press-fittingmargin between the upper case 12 and the stator core 28 is small. As aresult, the stator core 28 is easily press-fitted when the stator core28 is to be fixed to the upper case 12 and thus positional accuracy ofthe stator 29 with respect to the upper case 12 can be enhanced evenwhen the stator 29 is press-fitted and fixed to the upper case 12.Therefore, a gap space between the stator core 28 of the stator 29 andthe drive magnet 22 of the rotor 23 which face each other through theupper case 12 (partition wall) can be controlled with a high degree ofaccuracy.

Further, the inner peripheral face of the ring-shaped part 50 of thestator core 28 is formed with a plurality of inner side recessed parts53 to which each of three stator fixing protruding parts 85 is capableof being press-fitted and each of the stator fixing protruding parts 85is press-fitted to each of the inner side recessed parts 53. Therefore,the stator 29 (stator core 28) is positioned around the axial line “L”.Further, when the rotor 23 provided with the impeller 21 is rotated bythe magnetic drive mechanism structured of the drive coil 27, the statorcore 28 and the drive magnet 22, the stator 29 is prevented from beingturned around the axial line “L” by the reaction force. In addition, inthis embodiment, three stator fixing protruding parts 85 provided on theouter peripheral face of the center protruded part 80 are press-fittedto the inner side recessed parts 53 of the ring-shaped part 50 and thusstress at the time of press-fitting is easily released from each of thestator fixing protruding parts to the circumferential direction of thecenter protruded part 80. Therefore, deformation and damage of the uppercase 12 can be prevented when the stator 29 is press-fitted and fixed.

In addition, three stator fixing protruding parts 85 are provided withthe same shape as each other and three or more stator fixing protrudingparts 85 may be formed at an equal angular interval. Therefore, whenthree stator fixing protruding parts 85 are press-fitted and fixed tothe ring-shaped part 50, concentricity of the center protruded part 80of the upper case 12 with the stator core 28 is improved. Accordingly,the positional accuracy of the stator 29 with respect to the upper case12 is improved.

Further, in this embodiment, the stator 29 is covered by the pottingagent 16 as a sealing agent which is poured into the statoraccommodating room 83 and thus, even when a press-fitting margin betweenthe upper case 12 and the stator core 28 is small, the stator 29 can besurely fixed to the upper case 12 by the potting agent 16.

In addition, in this embodiment, the inner peripheral face of the tubeshaped part 84 of the center protruded part 80 is formed with the groove99 at a position corresponding to each of the stator fixing protrudingparts 85 formed on the outer peripheral face of the tube shaped part 84.Therefore, a thickness of the tube shaped part 84 of the centerprotruded part 80 can be set almost uniform over the entire periphery.As a result, shrinkage occurred in the center protruded part 80 when theupper case 12 is molded can be set uniform and thus the cylindricalityof the center protruded part 80 is improved.

Further, in this embodiment, the positioning part 88 and the statorfixing protruding parts 85 are formed at separated positions in thecircumferential direction and thus, even when the ring-shaped part 50 ofthe stator core 28 shaves the stator fixing protruding parts 85 made ofresin at the time of press-fitting, shavings are not attached to thepositioning part 88. Therefore, positioning in the axial line “L”direction of the stator 29 can be performed with a high degree ofaccuracy.

In addition, in this embodiment, the support shaft 24 rotatablysupporting the rotor 23 is fixed to the center of the inner side face ofthe bottom part 81 (face on the partitioned chamber 20 side) of thecenter protruded part 80 to which the stator core 28 is fixed.Therefore, a relative positional accuracy of the rotor 23 supported bythe support shaft 24 to the stator 29 is improved. Further, according tothis structure, the support shaft 24 is fixed to the bottom part 81 ofthe center protruded part 80 and the stator core 28 is fixed to theopening end 80 b side of the center protruded part 80 and thus the fixedpart of the stator 29 and the fixed part of the support shaft 24 areseparated from each other in the axial line “L” direction. Therefore,even when the tube shaped part 84 of the center protruded part 80 may bedeformed at the time of press-fitting and fixing of the stator 29, thefixing of the support shaft 24 is prevented from being unstable.

Other Embodiments

In the embodiment described above, each of the stator fixing protrudingparts 85 and each of the inner side recessed parts 53 are provided witha circular arc contour in cross section and the tip end on the outerperipheral side of the stator fixing protruding part 85 is press-fittedto the inner side recessed part 53 and gap spaces are provided bothsides in the circumferential direction. However, for example, it may bestructured that one of the cross-sectional shapes of the stator fixingprotruding part 85 and the inner side recessed part 53 is changed andboth sides in the circumferential direction of the stator fixingprotruding part 85 are press-fitted to the inner side recessed part 53and a clearance is provided between the tip end on the outer side in theradial direction and the inner side recessed part 53. In this case, atthe time of press-fitting, stress is restrained to occur the centerprotruded part 80 in the radial direction and thus deformation anddamage of the upper case 12 can be prevented. In accordance with anembodiment of the present invention, no inner side recessed part 53which is provided in the ring-shaped part 50 of the stator core 28 maybe formed. Further, in a case that the entire periphery on the outerperipheral side of the stator fixing protruding part 85 is press-fittedto the inner side recessed part 53, positioning in the circumferentialdirection and the radial direction of the stator 29 are performedsimultaneously. In addition, the cross sectional shapes of each of thestator fixing protruding part 85 and each of the inner side recessedpart 53 are not limited to a semicircular shape and a triangular shapeand a quadrangular shape may be used.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, rather than theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

1. A pump device comprising: a stator comprising: a stator core having aring-shaped part on a center side; and a drive coil which is woundaround the stator core; a rotor provided with an impeller and a drivemagnet which faces the stator through a predetermined distance on anouter peripheral side of the stator; and a partition wall which isdisposed between the stator and the rotor for separating a pump chamberin which the impeller is disposed from the stator; wherein the partitionwall is provided with a protruded part in a bottomed tube-like shapewhich is protruded on an inner side of the ring-shaped part; wherein anouter peripheral face of a tube shaped part structuring the protrudedpart is formed with a plurality of protruding parts which protrude fromparts in a circumferential direction to an outer side in a radialdirection; and wherein the stator core is fixed to the protruded part ina state that the plurality of the protruding parts is press-fitted tothe ring-shaped part.
 2. The pump device according to claim 1, whereinan inner peripheral face of the ring-shaped part of the stator core isprovided with a plurality of recessed parts to which each of theplurality of the protruding parts is capable of being press-fitted, andthe protruding parts are press-fitted to the recessed parts.
 3. The pumpdevice according to claim 2, wherein both side portions in thecircumferential direction of the protruding part are press-fitted to therecessed part, and a clearance is provided between a tip end on an outerside in the radial direction of the protruding part and the recessedpart.
 4. The pump device according to claim 2, wherein the plurality ofthe protruding parts is formed in a same shape as each other and isformed at three or more positions at an equal angular interval.
 5. Thepump device according to claim 4, wherein the protruding part isextended in an axial line direction along the outer peripheral face ofthe tube shaped part and is provided with a tapered face whoseprotruding amount to an outer side in the radial direction and to thecircumferential direction is increased from a side of a bottom part ofthe protruded part in the bottomed tube-like shape toward a side of anopening end of the protruded part, and a part of the protruding part onthe side of the opening end is press-fitted to the ring-shaped part ofthe stator core.
 6. The pump device according to claim 1, wherein thepartition wall is provided with a cylindrical tube part provided on anouter peripheral side of the protruded part and a circular ring-shapedpart which connects an opening end of the protruded part with thecylindrical tube part, the stator is accommodated in a circularring-shaped recessed part for accommodating the stator which is formedof the protruded part, the cylindrical tube part and the circularring-shaped part, and the stator is covered by a sealing agent which ispoured into the circular ring-shaped recessed part for accommodating thestator.
 7. The pump device according to claim 6, wherein the protrudedpart in the bottomed tube-like shape is provided with a protrudingportion which protrudes in an axial line direction from an opening ofthe circular ring-shaped recessed part for accommodating the stator on abottom part side of the protruded part, and an end of the protrudingpart on the bottom part side of the protruded part is reached to theprotruding portion.
 8. The pump device according to claim 7, wherein thepartition wall is a resin molded product, and an inner peripheral faceof the tube shaped part structuring the protruded part is formed with agroove at a position corresponding to the protruding part formed on theouter peripheral face of the tube shaped part.
 9. The pump deviceaccording to claim 8, wherein a support shaft which rotatably supportsthe rotor is fixed to an inner side face of the bottom part of theprotruded part, the rotor is provided with a bearing part in a tube-likeshape, the bearing part is disposed on an inner side of the protrudedpart in a state that the support shaft is inserted into a center hole ofthe bearing part, a washer for adjusting a position in the axial linedirection of the rotor is fitted between the bottom part of theprotruded part and the bearing part, the washer is formed with a turningprevention part protruding to an outer side in the radial direction froman outer circumferential edge portion of the washer, and the turningprevention part is fitted to the groove formed on the inner peripheralface of the tube shaped part.
 10. The pump device according to claim 6,wherein a support shaft which rotatably supports the rotor is fixed toan inner side face of the bottom part of the protruded part.
 11. Thepump device according to claim 1, wherein an outer peripheral face ofthe tube shaped part structuring the protruded part is provided with apositioning part which is abutted with the ring-shaped part of thestator core from a side of an opening end of the protruded part in thebottomed tube-like shape for positioning the stator in an axial linedirection, and the positioning part and the protruding part are formedat a separated position from each other in a circumferential direction.12. The pump device according to claim 1, wherein the pump devicecomprises: a first case which structures the partition wall and isprovided with a circular ring-shaped protruded part on an inner side ofan outer peripheral wall; a second case which is provided with acircular ring-shaped stepped part into which the circular ring-shapedprotruded part is coaxially inserted and which partitions the pumpchamber on an inner peripheral side of the circular ring-shaped steppedpart together with the first case; and an O-ring which is attached on acircular outer peripheral face of the circular ring-shaped protrudedpart and is crushed between the circular outer peripheral face of thecircular ring-shaped protruded part and a circular inner peripheral faceof the circular ring-shaped stepped part in a direction perpendicular toan axial line of the circular ring-shaped protruded part.
 13. The pumpdevice according to claim 12, wherein the first case is provided with acylindrical tube part formed on an outer peripheral side of theprotruded part and a circular ring-shaped part connecting an opening endof the protruded part with the cylindrical tube part, the stator isaccommodated in a circular ring-shaped recessed part for accommodatingthe stator which is formed of the protruded part, the cylindrical tubepart and the circular ring-shaped part, and the stator is covered by asealing agent which is poured into the circular ring-shaped recessedpart for accommodating the stator.
 14. The pump device according toclaim 13, wherein the second case comprises: a bottom plate part; a sidewall part in a ring shape which is stood up from an outer peripheralside portion of the bottom plate part; and a circular recessed partwhich is formed of the bottom plate part and the side wall part; aninner peripheral face on an upper side of the side wall part is formedwith the circular ring-shaped stepped part; and a liquid flow passage isstructured between the circular ring-shaped protruded part of the firstcase and the circular recessed part of the second case at a position onan inner side with respect to the circular ring-shaped stepped part. 15.A pump device comprising: a stator comprising: a stator core having aring-shaped part on a center side; and a drive coil which is woundaround the stator core; and a partition wall configured to separate apump chamber from the stator; wherein the partition wall is providedwith a protruded part in a bottomed tube-like shape which is protrudedon an inner side of the ring-shaped part; wherein an outer peripheralface of a tube shaped part structuring the protruded part is formed witha plurality of protruding parts which protrude from parts in acircumferential direction to an outer side in a radial direction; andwherein the stator core is fixed to the protruded part in a state thatthe plurality of the protruding parts is press-fitted to the ring-shapedpart.